科学家们已经做了无数实验，表明在改进人的行为方面，表扬比批评有效的多。 [

A、 ] Scientists have done countless experiments to show that praise is far more effective than criticism in improve human behavior. [

B、 ] Scientists have done countless experiments to show that praise is far more effective than criticism in improving human behavior. [

C、 ] Scientists have done countless experiments to show that praise is far much effective than criticism in improving human behavior. [

D、 ] Scientists have done countless experiments to show that praise is far more effective than criticism to improving human behavior.